// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_VIEWS_VIEW_MODEL_H_
#define UI_VIEWS_VIEW_MODEL_H_

#include <vector>

#include "base/logging.h"
#include "base/macros.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/views/views_export.h"

namespace views {

class View;
class ViewModelUtils;

// Internal implementation of the templated ViewModelT class. Provides
// non-templated "unsafe" methods for ViewModelT to wrap around. Any methods
// that allow insertion of or access to a View* should be protected, and have a
// public method in the ViewModelT subclass that provides type-safe access to
// the correct View subclass.
class VIEWS_EXPORT ViewModelBase {
public:
    ~ViewModelBase();

    // Removes the view at the specified index. This does not actually remove the
    // view from the view hierarchy.
    void Remove(int index);

    // Moves the view at |index| to |target_index|. |target_index| is in terms
    // of the model *after* the view at |index| is removed.
    void Move(int index, int target_index);

    // Variant of Move() that leaves the bounds as is. That is, after invoking
    // this the bounds of the view at |target_index| (and all other indices) are
    // exactly the same as the bounds of the view at |target_index| before
    // invoking this.
    void MoveViewOnly(int index, int target_index);

    // Returns the number of views.
    int view_size() const { return static_cast<int>(entries_.size()); }

    // Removes and deletes all the views.
    void Clear();

    void set_ideal_bounds(int index, const gfx::Rect& bounds)
    {
        check_index(index);
        entries_[index].ideal_bounds = bounds;
    }

    const gfx::Rect& ideal_bounds(int index) const
    {
        check_index(index);
        return entries_[index].ideal_bounds;
    }

    // Returns the index of the specified view, or -1 if the view isn't in the
    // model.
    int GetIndexOfView(const View* view) const;

protected:
    ViewModelBase();

    // Returns the view at the specified index. Note: Most users should use
    // view_at() in the subclass, to get a view of the correct type. (Do not call
    // ViewAtBase then static_cast to the desired type.)
    View* ViewAtBase(int index) const
    {
        check_index(index);
        return entries_[index].view;
    }

    // Adds |view| to this model. This does not add |view| to a view hierarchy,
    // only to this model.
    void AddUnsafe(View* view, int index);

private:
    // For access to ViewAtBase().
    friend class ViewModelUtils;

    struct Entry {
        Entry()
            : view(NULL)
        {
        }

        View* view;
        gfx::Rect ideal_bounds;
    };
    typedef std::vector<Entry> Entries;

#if !defined(NDEBUG)
    void check_index(int index) const
    {
        DCHECK_LT(index, static_cast<int>(entries_.size()));
        DCHECK_GE(index, 0);
    }
#else
    void check_index(int index) const
    {
    }
#endif

    Entries entries_;

    DISALLOW_COPY_AND_ASSIGN(ViewModelBase);
};

// ViewModelT is used to track an 'interesting' set of a views. Often times
// during animations views are removed after a delay, which makes for tricky
// coordinate conversion as you have to account for the possibility of the
// indices from the model not lining up with those you expect. This class lets
// you define the 'interesting' views and operate on those views.
template <class T>
class ViewModelT : public ViewModelBase {
public:
    ViewModelT<T>() { }

    // Adds |view| to this model. This does not add |view| to a view hierarchy,
    // only to this model.
    void Add(T* view, int index) { AddUnsafe(view, index); }

    // Returns the view at the specified index.
    T* view_at(int index) const { return static_cast<T*>(ViewAtBase(index)); }

private:
    DISALLOW_COPY_AND_ASSIGN(ViewModelT<T>);
};

// ViewModel is a collection of views with no specfic type. If all views have
// the same type, the use of ViewModelT is preferred so that the views can be
// retrieved without potentially unsafe downcasts.
typedef ViewModelT<View> ViewModel;

} // namespace views

#endif // UI_VIEWS_VIEW_MODEL_H_
